ExtractorAssignmentPattern elisions

[waldemarhorwat]

The ExtractorAssignmentPattern grammar includes elisions inside parameter lists, but it's a cover grammar for which the original grammar doesn't allow elisions, so one can't actually use elisions here. What is the intent here?

[rbuckton]

Essentially, there are two options to consider:

1. Remove Elision from ExtractorAssignmentPattern and instead depend on discards from the Discard (void) Bindings proposal.
2. Introduce Elision into a cover grammar for Arguments.

Ultimately, the choice for Elision may depend on the direction of the Discard (void) Bindings proposal, and as such may change in Stage 2 to match. We could always choose to follow (2) here, since we will want to support (1) regardless.